This invention relates to a method and an apparatus for conditioning the chill surface of a strip casting roll. More particularly, the invention relates to cleaning the peripheral surface of the casting roll by in-situ grit blasting to remove dirt, metal oxides and surface imperfections that accumulate or form on the chill surface during casting of metal strip.
It is known to use brushes, buffers, grinders, flapper type devices and the like for conditioning the peripheral or circumferential surface of a casting roll used to solidify a metal melt into continuous metal strip. These mechanical conditioning devices may be ineffective for completely removing tightly adherent metal oxide. If metal oxide is not completely removed, the molten metal may not uniformly wet the roll chill surface and the solidified strip may not be adherent to the surface of the roll. These conditioning devices also tend to cut or otherwise mark the surface of the casting rolls. Scratch or grinding lines left on the surface tend to form surface defects on the strip. These conditioning devices also have a tendency to vibrate the casting roll which may affect the meniscus causing blemishes and cracks on the strip surface. These conditions also are undesirable because for strips having wide widths the devices must be segmented causing inhomogeneous surface conditions such as forming lines at the joints between the segments. These lines or seams may cause differences in the cast strip due to the effect on heat extraction. Also, there is a tendency to remove desirable surface finish of the casting roll.
Accordingly, there remains a need for removing metal oxides from the chill surface of a casting roll without leaving grinding lines or gouges. There also remains a need for conditioning the chill surface without vibrating the casting roll.